Photographic products and processes



July 10, 1962 H. c. I-IAAs ET AL 3,043,692

PHOTOGRAPHIC PRODUCTS AND PROCESSES Filed Dec. 17, 1958 SILVER HALIDEEMULSION LAYER P-ACETAMIDOBENZENE SULFONATE OF A PARTIAL O-SODIUMSULFOBENZAL OF POLYVINYL ALCOHOL CONTAINING A OLOR-PROVIDING SUBSTANCEBLUE-SENSITIVE SILVER HALIDE EMULSION LAYER P-ACETAMIDOBENZENE SULFONATEOF A PARTIAL O-SODIUIVI SULFOBENZAL OF POLYVINYL ALCOHOL CONTAINING A 36YELLOW DYE DEVELOPER T RLAYER GREEN-SENSITIVE sILvER HALIDE MULSION LAYE0- \{P-ACETAMIDOBENZENE SULFONATE OF A as PARTIAL O-SODIUM SULFOBENZALOF POLYVINYL ALCOHOL CONTAINING A 26 T MAGENTA DYE DEVELOPER XX 24\{lNTERLAYER 22 RED-sENsITIvE SILVER HALIDE EMULSION LAYER- 20P-ACETAMIDOBENZENE SULFONATE OF A PARTIAL O-SODIUM SULFOBENZAL OFPOLYVINYL ALCOHOL CONTAINING A cYAN DYE DEVELOPER SUPPORT FIG.2

' INVENTORS MQ.M

United rates The present invention is concerned with photography andmore particularly with novel photographic products and novelphotographic processes utilizing said products.

One object of thisinvention is to provide novel photosensitive elementsfor color diffusion transfer processes comprising at least one silverhalide emulsion layer and at least one layer of a polymeric materialhaving a colorproviding substance disposed therein, said polymeric layorbeing an acylamidobenzene sulfo ester of a partial sulfobenzal ofpolyvinyl alcohol.

Another object of this invention is to provide improved color diffusiontransfer processes utilizing said photosensitive elements.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

The invention accordingly comprises the several steps and the relationand order of one or more of such. steps with respect to each of theothers, and the product possessing the features, properties and therelation of elements which are exemplified in the following detaileddisclosure, and the scope of the application of which will be indicatedin the claims.

For a fuller understanding of the nature and objects of the invention,reference should be had to the following "detailed description taken inconnection with the accompanying drawing wherein:

FIGURE 1 is a diagrammatic cross-sectional view of one embodiment of aphotosensitive element of this invention; and

FIG. 2 is a diagrammatic cross-sectional view of one embodiment of amultilayer photosensitive element within the scope of this invention.

The present invention is particularly related to color diffusiontransfer processes. In such processes a photosensitive element includinga silver halide emulsion layer is exposed to create therein a latentimage. The latent image is developed and, concurrent with and under thecontrol of this development, an imagewise distribution of mobilecolor-providhrg substances is formed. At least aportion of thesecolor-providing substances is transferred by means of an alkalineaqueous processing liquid to a superposed image-receiving layer to forma color image thereon. As examples of such processes, mention may bemade of the processes disclosed and claimed in the copending U.S.application of Howard G. Rogers, Serial No. 748,421, filed July 14,1958, as a continuation-in-part of U.S. application, Serial No. 415,07filed March 9, 1954, and now abandoned, said continuation-impartapplication now U.S. Patent 2,983,606 issued May 9, 1961, wherein dyedevelopers (i.e., compounds which contain in the same molecule both thechromophoric system of a dye and also a silver halide developingfunction) are the colorsproviding substances, the processes claimed anddisclosed in U.S. Patent No. 2,647,049, issued July 28, 1953,

to Edwin H. Land, wherein color developers are employed to develop thelatent image and color couplers are the color-providing substances, andthe processes dis- In an especially useful mode of carrying out colordiffusion transfer processes such as described above, thecolor-providing substances are disposed in a separate alkali-permeablelayer in the photosensitive element. The separate alkali-permeable layermay be placed either in front of or behind the photosensitiveemulsionwith which it is associated; however, in a preferred embodimentit is placed behind, i.e., on the side of the emulsion which is mostdistant from the photographed subject when the emulsion is exposed, andpreferably also adapted to be most distant from the image-receivingelement when in superposed relationship therewith. In carrying out theprocesses, the photosensitive element is exposed and wetted with anaqueous alkaline processing solution, for example, by immersing,coating, spraying, flowing, etc., in the dark, and the photosensitiveelement is superposed prior to, during or after wetting on animage-receiving element. In a preferred embodiment the aqueous alkalineprocessing solution contains a viscosity-increasing compound andisapplied to the photosensitive element in a substantially uniform layerasthe photosensitive element is brought into superposed position withthe image receiving element. The alkaline aqueous processingsolutionpermeates the photosensitive emulsion and alkali permeablelayers and solubilizes the color-providing substances to provide asubstantially uniform distribution of the color-providing substancestherein. As the processes proceed, the exposed silver halide image isdeveloped and an imagewise distribution of mobile color-providingsubstances is formed. At least a portion of the color-providingsubstances is transferred to and imbibed on the image-receiving elementto form the image there on. The image is viewed by stripping theimage-receiving element from the photosensitive element.

When the color-providing substances are incorporated into a separatealkali-permeable layer, it is desirable that said alkali-permeable layerhave good dry adhesion to the other layers present in order to withstandthe stresses and strains such a layer would be normally subjected toduring, for example, coating operations, and especially to withstand thestresses and strains which are encountered if the photosensitive elementis a part of a roll film unit. Such adhesion must be achieved in thepresence of relatively high amounts of the color-providing substanceswhich generally have little or no adhesiveness in themselves and whichoften have an adverse effect on the bonding. It is furtherdesirable, andno less important, that said alkali-permeable layers have good wetadhesion to the other layers present; otherwise, during processing, uponstripping the image-receiving element.

from the photosensitive element, delamination may take place andportions of the photosensitive element would adhere to the surface ofthe image-receiving element and mar the quality of the transfer image.#It is still further desirable that the alkali-permeable layer readilyrelease the color-providing substances in order to make the maxi? mumamount of said materials available for forming the positive image. Inthe past, film-forming polymers such, for example, as cellulose acetatehydrogen phthalate have been proposed as materials for thealkali-permeable layers.

It has been discovered that when the colorrproviding substances aredisposed in polymeric layers comprising the acylaminobenzene sulfoesters of partial sulfobenzals of polyvinyl alcohol, such polymersprovide wet and dry adhesion which is superior to that obtained withcellulose acetate hydrogen phthalate, and, further, said polymersreadily release the color-providing substances.

The ability of the polymers of this invention to release thecolor-providing materials is especially demonstrable when dye developersare the color-providing materials,

contain in the same molecule both the chromophoric system of a dye andalso a silver halide developing function. By a silver halide .developingfunction is meant a radical which is capable of developing an exposedsilver halide image. Particularly useful dye developers are those inwhich the silver halide developing function is provided by a benzenoiddeveloping radical. A preferred benzenoid developing radical in suchcompound is a hydroquinonyl group. Examples of representative dyedevelopers are given in the previously mentioned US. application ofHoward G. Rogers, Serial No. 748,421. Additional useful dye developersare described in the following copending US. applications:

Application Serial No. 449,514, filed August 12, 1954, in

' the names of Elkan R. Blout and Myron S. Simon.

Application Serial No. 471,542, filed November 26, 1954, in the names ofElkan R. Blout, Saul G. Cohen, Milton Green, Howard G. Rogers, Myron S.Simon and Robert B. -Woodward.

Application Serial No. 478,922, filed December 30, 1954,

r in the names of Elkan R. Blout, Marilyn R. Cohler,

Milton Green, Myron S. Simon and Robert B. Woodward.

Application Serial No. 612,045, filed September '25, 1956, in the namesof Elkan R. Blout, Milton Green and Howard 6.. Rogers.

Application Serial No. 612,052, filed September 25, 1956, in the namesof Milton Green and Howard G. Rogers.

Application Serial No. 612,053, filed September 25, 1956,

. in the name of Myron S. Simon.

Application Serial No. 612,054, filed September 25, 1956, in the namesof Helen P. Husek and Myron S. Simon.

Application Serial No. 612,055, filed September 25, 1956,

. in the "name of Helen P.-Husek.

Application Serial No. 755,804, filed August 18,1958, in the namesofElkan R. Blout, Saul G. Cohen, Milton Green, and Myron S. Simon.

' In color difiusion transfer processes employing dye developers the dyedeveloper, 'as mentioned previously for color-providing substances ingeneral, is preferably placed in a separate alkali-permeable layerbehind the photosensitive layer. Uponprocessing, the alkaline aqueousprocessing solution permeates to the separate alkalipermeable layer'andsolubilizes the dye developer therebibed-on a superposed image-receivingelement to create thereon the positive dye image. In such processes theimmobilization of the dye developers in the exposed areas is apparentlydue,'at least, in part, to a change in the solubility characteristics ofthe dye developer upon oxidation, -It may also be due in part to atanning .eflect on the emulsion by the oxidized developer. 7

FIG. 1 of the accompanying drawing illustrates one embodiment of aphotosensitive element for use in 'color diffusion transfer processeswherein a p-acetamidobenzene sulfonate of a partially acetalizedo-sodium sulfobenzal of polyvinyl alcohol is used as the material for aseparate' alkali-permeable layer. The photosensitive element showntherein comprises a support 10, a layer 12 of a pacetamidobenzenesulfonate of'a partially acetalized sodium sulfobenzal of polyvinylalcohol containing a color-providing substance and a photosensitivelayer 14. i In preparing photosensitive elements of the type men-'tioned above and in preparing other photosensitive elements within thescope of this invention, ,the polymeric layers may be'convenientlyapplied from coating solutions containing the desired polymer; Thepreferred coating solutions comprise 2 to of polymer; however, thisamount-may be varied to suit particular needs. The

coating and drying operations may be carried out according to procedureswell known to the art. The colorproviding substances which are to bedisposed in the separate alkali-permeable layer may be incorporated intothe coating solution and applied therewith, or they may be imbibed ontothe layer after its application. When the color-providing substances areincorporated into the coating solutions, they may be dispersed orsolubilized therein, depending upon the color-providing substanceitself, the solvent used and the state desired for the diifusiontransfer processes. As examples of suitable solvents which can be usedin preparing'the coating solutions, mention may be made of methanol, 95%ethanol, and methanol-tetrahydrofuran mixtures. When the coatingsolution is applied directly to a support such, for example, as baryta,cellulose acetate, etc., said support may be first subcoated to furtherenhance the adhesion.

The polymers of this invention are also suitable as materials foralkali-permeable layers in integral multilayer photosensitive elementsfor use in multicolor diffusion transfer processes. As an example ofsuch photosensitive elements, mention may be made of the photosensitiveelements disclosed and claimed in the copending US. application of EdwinH. Land and Howard vG. Rogers, Sen'alNo. 565,135, filed February 13,1956, wherein at least two selectively sensitized photosensitive strataare superposed on a single support and are processed, simultaneously andwithout separation, with a single common image-receiving element. Asuitablearrangement of this type comprises a support carrying ared-sensitive silver halide emulsion stratum, a greensensitive silverhalideemulsion stratum, and a blue-sensitive silver halide emulsionstratum, said emulsions having associated therewith, respectively, acyan dye developer,

a magenta dye developer and a yellow dye developer. In one of thepreferred embodiments of photosensitive elements of this type, the dyedevelopers are disposed in separate alkali-permeable layers behind thephotosensitive silver halide emulsion stratum with which they areassociated. As in monochromatic photosensitive elements, the polymers ofthis invention, when used as materials for the alkali-permeable layers,provide superior wet and dry adhesion, as compared with celluloseacetate hydrogen phthalate, and also readily release the color-providingsubstances. When the polymers of this invention are used in suchmulticolor film units, at least one and usually all the color-providingsubstances are disposed in layers comprising the polymers of thisinvention. However, it should be understood that in certain instances itmay be desirable for reasons such, for example, as permeation rates,transfer rates, etc., to dispose some of the colorproviding substancesin the silver halide emulsions or in alkali-permeable layers ofmaterials other than those disclosed herein.

A multilayer photosensitive element of the type mentioned above isillustrated in FIG. 2 of the accompanying drawing. A support 20 carriesa layer 22 of a pacetamidobenzene sulfonate of a'partial o-sodiumsulfobenzal of polyvinyl alcohol containing a cyan dye developer; alayer 24 of a red-sensitive silver halide emulsion; an interlayer 26,e.g., polyvinyl alcohol, gelatin, etc.; a layer 28 of ap-acetamidobenzene sulfonate of a partial o-sodium 'sulfobenzal. ofpolyvinyl alcohol containing a magenta dye developer; a layer 30 of agreen-sensitive silver halide emulsion; an interlayer 32; a layer 34 ofa p-acetamidobenzene sulfonate of a partial o-sodium sulfobenzal ofpolyvinyl alcohol containing a yellow dye developer; and an outermostlayer 36 of a blue-sensitive silver halide emulsion. In certaininstances, for example, when the yellow dye developer is not present ina state capable of functioning as a filter, a yellow filter-is placed ininterlayer. 32. g 1 7 Although the mixed sulfo ester-acetal polymerlayers in the photosensitive element of FIG. 2 are shown principallyadhered to gelatin or polyvinyl alcohol layers, it

should be noted that the polymers of this invention show good adhesionto hydrophilic, alkali-permeable film-forming materials in general. As aresult of this, wide discretion may be exercised in selectingfilm-forming materials as carriers for the silver halide emulsion,interlayers, and other layers which may be adjacent to the copolymerlayers. For example, one may replace gelatin, which is the carrierusually used in the silver halide emulsion layer, in whole or in part,with gelatin substitutes such, for example, as cellulose ethers,polyvinyl alcohols, partially hydrolyzed organic esters of polyvinylalcohols, acetals of polyvinyl alcohols, etc. Similar discretion may beexercised in selecting the film-forming materials for the interlayersand other layers. In certain instances, if desired, the polymers of thisinvention may be used as the carrier in the iuterlayers and other layerswhich may be present.

' Although the polymers of this invention provide good adhesion in andby themselves, in certain instances their adhesion to adjacent layersmaybe enhanced by incorporating a small amount of said polymers into thelayers to which they are to be adhered. The amount of polymer, soincorporated, may be varied to suit particular needs; generally,however, an amount comprising about by weight, of the adjacentcarriermaterial will provide the increased adhesion.

Both the monochromatic and multicolor photosensitive elements within thescope of this invention may be used in roll films which contain aplurality of photosensitive frames. The photosensitive elements of thisinvention are especially useful in composite roll films intended for usein a Polaroid Land Camera, sold by Polaroid Corporation, Cambridge 39,Massachusetts, or a similar camera structure such, for example, as thecamera forming the subject matter of US. Patent No. 2,435,717, issued toEdwin H. Land on February 10, 1948. In general, such composite rollfilms comprise -a photosensitive roll, a roll of image-receivingmaterial and a plurality of pods containing an aqueous alkalineprocessing solution. The rolls and pods are so associated with eachother that, upon processing, the photosensitive element may besuperposed on the image-receiving element and the pods may be rupturedto spread the aqueous alkaline processing solution between thesuperposed elements. The nature and construction of the pods used insuch units are well known to the art. See, for example, U.S. PatentsNos. 2,543,181 and 2,634,886, issued to Edwin H. Land.

The polymers for use in preparing the photosensitive elements of thisinvention may be prepared by partially acetalizing polyvinyl alcoholwith an ortho-, metaor para-benzaldehyde sulfonic acid and then reactingthe resulting partial acetai with an ortho-, metaorpara-acylamidobenzene sulfonyl chloride. Suitable polyvinyl alcohols,for use in the preparation, may be selected from the low, medium andhigh viscosity, partially and completely hydrolyzed polymers which arecommercially available. As examples of such polymers, mention may bemade of Elvanol 70-05 (low viscosity, completely hydrolyzed), Elvanol31-31 (medium viscosity, about 76- 79% hydrolyzed), trade names of E. I.du Pont de Nemours & Co., Wilmington, Delaware) and Gelvatol 2-75 (tradename of Shawinigan Products Corp, New York, N.Y., for high viscosity,completely hydrolyzed polyvinylalcohol). The preferred acylamidobenzenesulfonyl chlorides, for use in the preparation, are those in which theacyl group comprises less than four carbon atoms, e.g., acetamidobenzenesulfonyl chloride and propionylamidobenzene suifonyl chloride. Inpreparing the polymers of this invention, the degree to which thehydroxyl groups are substituted by benzal or ester groups and the ratioof benzal substituted hydroxyl groups to sulfo esterified hydroxy groupscan usually be varied to suit particular needs; however, the polymerswhich have been found to be particularly useful are those in which thehydroxyl groups are substantially fully substituted and in which saidratio is about 1.4 to 1. Although it is contemplated that thepolymersmay be used as the free acid or as a salt, they are preferably employedas a salt because of their greater stability in such form. The preferredsalts are those which are derived from bases which are capable offorming water-soluble salts, e.g., alkali metals, ammonia, amines, etc.When it is desired to have increased water resistance, hydrophobic aminesalts of the polymers may be employed.

The following nonlimiting example illustrates the preparation ofpolymers within the scope of this invention:

Example 1 44 gms. of polyvinyl alcohol 70-05were placed in 400 m1. ofglacial acetic acid'and gms. of o-benzaldehyde sulf-onie' acid (sodiumsalt) and 2 gms. of p-toluene sulfonic acid were added. The reaction wasstirred and heated at 60 C. under nitrogen, for eighteen hours. Theproduct was isolated by precipitation into acetone, purified byreprecipitation from methanol into acetone and dried, undervacuum, at 40C. A sulphur analysis on the product indicated 41.6% of the hydroxylgroups remained unsubstituted.

10 gms. of the partial o-sodium sulfobenzal of polyvinyl alcohol 70-05,prepared as above, were dispersed in 75 gms. of dry pyridine. 14.61 gms.of p-acetamidobeuzene sulfonyl chloride were added 'and the mixture wasstirred and heated at 40 C. The polymer was isolated by precipitationinto acetone, purified by reprecipitation from water into acetone anddried, under vacuum at 45 C.

The following nonlimiting examples illustrate the preparation and use ofphotosensitive elements within the scope of this invention.

Example 2 A methanol-tetrahydrofuran coating solution (1 to l, byvolume) comprising 2% of the polymer, as prepared in Example 1, and 3%of 1-phenyl-3-N-n-hexyl-carboxamido 4[p-(2',5-dihydroxyphenethyl)-phenylazo]-5- pyrazolone (prepared by theprocesses disclosed in the previously mentioned copending US.application, Serial No. 612,045) was coated on a gelatin-subcoatedcellulose acetate support. When the coating solution had dried, a silverhalide emulsion layer was applied. 7

The above photosensitive element was exposed and then processed byspreading an aqueous processing solution comprising:

Percent Sodium carboxymethyl cellulose 5.0 Sodium hydroxide 2.01-phenyl-3-pyrazolidone 0.6

G-nitrobenzimidazole 0.12 2,5 -biseethyleneiminohydroquinone 0.4

between said photosensitive element and an image-receiving element assaid elements were brought into superposed relationship. Theimage-receiving element comprised a cellulose acetate coated barytapaper which had been coated with an ethanol solution containing 4% ofNylon Type F 8 (trade name of El. du Pont de Nemours & Co., Wilmington,Delaware, for N-methoxymethyl polyhexamethylene adipamide). After animbibition period of approximately one minute, the image-receivingelement was separated and contained a dense yellow positive dye image ofthe photographed subject. No signs of wet delamination were observed. v

In the above example, the dry adhesion of the polymer layer was testedby adhering a strip of an adhesive film to the photosensitive element,stripping it from the element and observing for delamination. Thephotosensitive element, prepared in the above example, was superior tosimilar photosensitive elements prepared with cellulose acetate hydrogenphthalate as the dye carrier. The dry adhesion was further tested bybending the photosensitive phthalate as the carrier, without showingsigns of delamination.

As mentioned previously the polymers of this invention may be used inintegral multilayer photosensitive elements such as those disclosed incopending application No. 748,421. As examples of suitable coatingsolutions which may be used to apply the cyan, magenta and yellow dyedeveloper layers in such elements mention may be made of:

(l) A tetrahydrofuran-methanol solution (1 to 1, by volume) comprising5.5 %*of 1,4-bis-[B-(2',5'-dihydroxyphenyl)-isopropylamino]-anthaquinone(a cyan dye developer prepared in a manner similar to that disclosed inthe previously mentioned copending application No. 478,922) and 2% ofthe polymer as prepared in Example 1. a

(2) A tetrahydrofuran-methanol solution (1 to 1, by volume) comprising3.5% of2-[p-(2',5'-dihydroxyphenethyle)-phenylazo]-4-n-propoxy-1-naphthol (amagenta dye developer prepared in a manner similar to that disclosed inthe previously mentioned copending application No. 612,045) and 2% ofthe polymer, as prepared in Example 1.

(3) A tetrahydrofuran-methanol solution (1 to 1, by volume) comprising3% of 1-phenyl-3-N-n-hexyl-carboxamido-4-[p-(2',5'-dihydroxyphenethyl)phenyla'zo] pyrazalone, (a yellow dye developer prepared in a mannersimilar to that disclosed in the previously mentioned copendingapplication No. 612,045) and 2% of the polymer as prepared in Example 1.

The polymers of this invention are further suitable for use in screentype photosensitive elements such as disclosed in the aforementionedapplication of Howard G. Rogers, Serial No. 748,421, and also thecopending application of Edwin H. Land, Serial No. 448,441, filed August9, 1954, wherein at least two selectively sensitized silver halideemulsions are arranged in the form of a screen and the color-providingsubstances, as in multilayer photosensitive elements, are preferablyplaced in a separate alkali-permeable layer in back of thephotosensitive emulsion with which they are associated.

In certain instances, minor irregular patterns, e.g., slight waviness,may be observed in the monochrome and multicolor transfer imagesproduced from photosensitive elements wherein the color providingsubstances are disposed in hydrophilic layers. Such patterns, whichdetract only slightly from the good overall photographic quality of theimage, appear to occur most frequently when aqueous coating solutionsare usedto apply the layers which are to be directly over the layerscontaining the color-providing substances. Although the cause of suchpatterns is not known for certain, it is believed that in the coatingoperation the water of the coating solution permeates the hydrophiliclayers and causes slight swellings and distortions which are transmittedto the transfer image. It has been discovered that such minor irregularpatterns may be substantially eliminated by incorporating a small amountof a hydrophobic polymer into the hydrophilic layers. As examples ofhydrophobic polymers which have been found to be especially useful,mention may be made of cellulose acetate and cellulose nitrate. Theamount of hydrophobic polymers added may be varied to suit particularneeds. Usually an amount equal to about 25% .of the hydrophilic polymerwill produce the desired results.

Since certain changes may be made in the above product and processwithout departing from the scope of the invention herein involved, itisintended that all matter contained in the above description or shownin the accompanying drawing shall be interpreted as illustrative andnotina sense.

What is claimed is:

1. A photosensitive element for difiusion transfer color processes, saidelement comprising a support, a polymeric layer having a color-providingsubstance selected from the group consisting of dyes and dyeintermediates dis- -posed therein and a silver halide emulsion layer,said polymeric layer comprising a. polymer prepared by acetalizing aportion of the hydroxy groups of polyvinyl alcohol with a compoundselected from the group consisting of ortho, metaand para-benzaldehydesulfonic acids and then esterifying the resulting partial acetal with acompound selected from the group consisting of ortho-,

metaand para-acylamidobenzene sulfonyl chlorides, the

acyl group of said chlorides comprising less than 4 carbon atoms.

2. A photosensitive element as defined in claim 1 wherein saidcolor-providing substance is a dye developer.

3. A photosensitive element as defined in claim 1 wherein said polymericlayer is between said support and said silver halide emulsion layer.

4. A photosensitive element as defined in claim 1 wherein the hydroxylgroups of said polymer are substantially fully substituted.

5. A photosensitive element as defined in claim 1 wherein the ratio ofbenzal substituted hydroxyl groups to sulfo esterified hydroxy groups insaid polymer is about 1.4 to 1.

6. A photosensitive element as defined in claim 1 wherein said polymericlayer comprises a salt of said polymer.

7. A photosensitive element as defined in claim 6 wherein said salt isan alkali metal salt.

8. A photosensitive element for color difiusion transfer processes, saidelement comprising a plurality of photosensitive silver halideemulsions, each of said emulsions being selectively sensitized todifferent portions of the spectrum, a dye developer associated with eachof said emulsions, said dye developer being a compound which containswithin the same molecule a chromophoric system of a dye and also asilver halide developing function, atleast one of said dye developersbeing disposed in a polymeric layer contiguous with the emulsion withwhich it is associated, said polymeric layer comprising a polymerprepared by acetalizing a portion of the hydroxy groups of polyvinylalcohol with a compound selected from the group consisting of ortho-,metaand para-benzaldehyde sulfonic acids and then esterifying theresulting partial acetal with a compound selected from the groupconsisting of ortho-, metaand para-acylamidobenzene sulfonyl chlorides,the acyl group of said chlorides comprising less than 4 carbon atoms.

9. A photosensitive element as defined in claim 8 wherein the hydroxylgroups of said polymer are substantially fully substituted.

10. A photosensitive element as defined in claim 8 wherein the ratio ofbenzal substituted hydroxyl groups to sulfo esterified hydroxyl groupsin said polymer is about 1.4 to 1.

11. A photosensitive element as defined in claim 8 wherein saidpolymeric layer comprises a salt of said polymer.

12. A photosensitive element as defined in claim 11 wherein said salt isan alkali .metal salt.

13. In a process of forming a photographic image in color wherein thelatent image contained in an exposed silver halide emulsion layer of aphotosensitive element is developed to provide an imagewise distributionof C0101? providing substances selected from the group consisting ofdyes and dye intermediates in said emulsion and said imagewisedistribution of color-providing substances is transferred by an aqueousalkaline processing solution to a superposed image-receiving layer toimpart to said image-receiving layer a color image, the improvementcomprising having the color-providing substance in a polymeric layerbehind the silver halide emulsion layer and, during processing,permeating said photosensitive element with said aqueous alkalineprocessing solution and solubilizing said color-providing substance fromsaid polymeric layer, said polymeric layer comprising a polymer preparedby acetalizing a portion of the hydroxy groups of polyvinyl alcohol witha compound selected from the group consisting of ortho-, metaandparabenzaldehyde sulfonic acids and then esteri-fying the resultingpartial acetal with a compound selected from the group consisting ofortho-, metaand para-acylamidobenzene sulfonyl chlorides, the acyl groupof said chlorides comprising less than 4 carbon atoms.

14. A process as defined in claim 13 wherein the hydroxy-l groups ofsaid polymer are substantially fully su stituted.

15. A process as defined in claim 13 wherein the ratio of benzalsubstituted hydroxyl groups to sulfo esterified hydroxyl groups in saidpolymer is about 1. 4 to 1.

16. A process as defined in claim 13 wherein said polymeric layercomprises a salt of said polymer.

17. A process as defined in claim 16 wherein said salt is an alkalimetal salt. I

18. In a process of forming transparent images in color which comprisesexposing a photosensitive emulsion containing a silver halide emulsionlayer and a polymeric layer, said polymeric layer containing a dyedeveloper, said dye developer being a compound which contains within thesame molecule a chromoph'oric system of a dye and also a silver halidedeveloping function, permeating said photosensitive element with anaqueous alkaline processing solution and solubilizing at least a portionof said d-ye developer from said polymeric layer, developing the latentimage in the exposed emulsion in the presence of said dye developerwhereby said dye developer is immobilized in the exposed areas but ismobile in unexposed areas, thereby providing an imagewise distributionof mobile dye developer, and transferring at least a portion of saidmobile dye developer to a superposed image-receiving layer to form apositive image, the improvement comprising having the dye developer in apolymeric layer comprising a polymer prepared by acetalizing a portionof the hydroxy groups of polyvinyl alcohol with a compound selected fromthe group consisting of ortho-, metaand para-benzaldehyde sulfonic acidsand then esterifying the resulting partial acetal with a compoundselected from the group consisting of ortho-, metaandpara-acylamidobenzene sulfonyl chlorides, the acyl group of saidchlorides comprising less than 4 carbon atoms.

19. A process as defined in claim 18 wherein the hydroxyl groups of saidpolymer are substantially fully substituted.

20. A process as defined in claim 18 wherein the ratio of benzalsubstituted hydroxyl groups to sulfo esterified hydroxyl groups in saidpolymer is about 1.4 to l.

21. A process as defined in claim 18 wherein said polymeric layercomprises a salt of said polymer.

22. A process as defined in claim 21 wherein said salt is an alkalimetal salt.

References Cited in the file of this patent UNITED STATES PATENTS2,546,400 Murray Mar. 27, 1951 2,774,668 Rogers Dec. 18, 1956 2,892,710Cohler et a1. June 30, 1959 FOREIGN PATENTS 484,306 Canada June 24, 1952

1. A PHOSTOSENSITIVE ELEMENT FOR DIFFUSION TRANSFER COLOR PROCESSES,SAID ELEMENT COMPRISING A SUPPORT, A POLYMERIC LAYER HAVING ACOLOR-PROVIDING SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF FYES ANDDYE INTERMEDIATES DISPOSED THEREIN AND A SILVER HALIDE EMULSION LAYER,SAID POLYMERIC LAYER COMPRISING A POLYMER PREPARED BY ACETALIZING APORTION OF THE HYDROXY GROUPS OF POLYVINYL ALCOHOL WITH A COMPOUNDSELECTED FROM THE GROUP CONSISTING OF ORTHO-, META- ANDPARA-BENZEALDEHYDE SULFONIC ACIDS AND THE ESTERIFYING THE RESULTINGPARTIAL ACETAL WITH A COMPOUND SELECTED FROM THE GROUP CONSISTING OFORTHOMETA-AND PARA-ACYLAMIDOBENZENE SULFONYL CHLORIDES THE ACYL GROUP OFSAID CHLORIDES COMPRISING LESS THAN 4 CARBON ATOMS.